How to Append a world with HDRi and nodes from another blendfile?
To append an HDRi texture from another blend file along with the nodes :

append the world
select the world settings from the properties panel
Click on the browse world settings to be linked
In that you will see the appended world with the name World.001 if it's not named and will appear with the name if it's named in the appended .blend file


The world will be appended along with the node setup